Studies by the Vega group suggested a mechanistic link between a persistent high level expression of the phosphorylated FoxO1 (p-FoxO1Ser319) in the endometrial epithelial compartment and disturbed endometrial homeostasis, steroid bioavailability and failed uterine receptivity in obese and hyperinsulinemic women with PCOS [46,68]. This evidence concerns the gene FOXO1 and polycystic ovary syndrome.